Audio Gain Metadata Check for Downmix Clipping Protection
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Solution Overview
Problem
Existing audio signals face issues with clipping artifacts during downmixing and amplification due to insufficient or absent dynamic range control metadata, leading to undesirable audio quality in various listening environments.
Innovation Solution
A method and apparatus that determine and modify or add gain values to ensure clipping protection by comparing and overriding or adding gain values based on received metadata, ensuring sufficient attenuation to prevent clipping during downmixing and amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic range control metadata is embedded in the audio stream for artistic dynamic range compression, then the dynamic range can be controlled according to listening conditions, but the metadata may not include sufficient gain values to prevent downmix clipping
Solution Approach 1:
The receiver proactively determines whether the received dynamic range control metadata contains sufficient gain values for clipping protection before applying the metadata. By performing this check in advance and computing additional gain values when needed, the system ensures clipping protection is in place before the downmix operation occurs, preventing clipping artifacts rather than correcting them afterward.
Solution Approach 2:
The system evaluates the sufficiency of received gain values by comparing them against computed gain values that would be required for clipping protection. This feedback mechanism allows the receiver to identify when the embedded metadata is insufficient and automatically supplement it with computed values, ensuring both artistic dynamic range control and clipping protection are achieved.
2Productivity
If the receiver applies received dynamic range control metadata without verification, then processing is simple and fast, but clipping artifacts may occur in the downmixed signal
Solution Approach 1:
Instead of fully verifying the sufficiency of received gain values (which would be computationally expensive), the system performs a partial check by comparing received gain values with computed gain values only when needed. This selective approach maintains high processing speed for most cases while providing clipping protection when the received metadata is insufficient.
Solution Approach 2:
The receiver autonomously determines whether the received dynamic range control metadata is sufficient for clipping protection and self-corrects by computing additional gain values when needed. This self-service mechanism eliminates the need for external verification or retransmission, maintaining processing efficiency while ensuring clipping protection.
3Reliability
If computed gain values are always used for clipping protection, then clipping is prevented, but the artistic dynamic range control intended by the content creator may be compromised
Solution Approach 1:
The system applies different gain values to different parts of the audio signal based on local needs. When the received dynamic range control metadata provides sufficient clipping protection, those original gain values are used to preserve artistic intent. When clipping protection is insufficient, computed gain values are applied only to the extent necessary to prevent clipping, minimizing interference with the artistic dynamic range control.
Solution Approach 2:
The system dynamically adjusts the gain parameter based on the sufficiency check. If the received gain values are sufficient for clipping protection, they are used as-is to maintain artistic integrity. If they are insufficient, the gain values are modified by combining received and computed values, changing the parameter only to the extent necessary to achieve both clipping protection and artistic fidelity.
Data Source
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AI summary
The application describes a method and an apparatus to prevent clipping of an audio signal when protection against signal clipping by received audio metadata is not guaranteed. The method may be used to prevent clipping for the case of downmixing a multichannel signal to a stereo audio signal. According to the method, it is determined whether first gain values (4) based on received audio metadata are sufficient for protection against clipping of the audio signal. The audio metadata is embedded in a first audio stream (1). In case a first gain value (4) is not sufficient for protection, the respective first gain value (4) is replaced with a gain value sufficient for protection against clipping of the audio signal. Preferably, in case no metadata related to dynamic range control is present in the first audio stream (1), the method may add gain values sufficient for protection against signal clipping.